Week 1): Male & Female Reproductive Embryology

When is genotype established?

Fertilization

During what period is the embryo indifferent?

Weeks 1-6

When does phenotypic sexual differentiation begin?

Week 7

When can external genitalia be recognized?

Week 12

When does phenotypic differentiation complete?

Week 20

What gene determines phenotypic sexual differentiation, and what does it encode for?

SRY, TDF

TDF stimulates the production of ___ by ___ cells the production of ___ by ___ cells

Testosterone, Leydig, Mullerian inhibiting factor, Sertoli

When testosterone and MIF are produced, a ___ phenotype results

Male

Where do primordial germ cells migrate from and to?

From yolk sac to primary sex cords

What is the general progression of the genitalia of the indifferent embryo?

Gonads to genital ducts to primordial genitalia

What structure provides the basis for the formation of the urinary and reproductive systems, and which embryological layer is it derived from?

Urogenital ridge, intermediate mesoderm

What are the primary outgrowths from the urogenital ridge in males?

Mesonephric (Wolffian) duct

What are the primary outgrowths from the urogenital ridge in females?

Paramesonephric (Mullerian) ducts

Where does the caudal tip of the mesonephric/paramesonephric ducts project?

Posterior wall of the urogenital sinus

Mesonephric tubules mostly regress, but a few form ___ proximally and ___ distally

Bowman’s capsules, testicular efferent ductules

What specific structures are formed by the mesonephric duct?

Epididymis, ductus deferens, seminal vesicles, ejaculatory duct

What specific structures are formed by the paramesonephric ducts?

Uterine tubes, uterus, cervix, upper third of the vagina

What forms the lower 2/3 of the vagina? (embryological layer)

Urogenital sinus (endoderm)

The primary sex cords develop from the ___

Gonadal ridge

In females, the primary sex cords extend into the medulla and develop a ___, which eventually degrades

Rete ovarii

The ___ extends from the medial surface of ovaries to the uterus at the junction of the ovarian tubes, forming the ___ after development

Gubernaculum, ovarian ligament

The gubernaculum terminates at the ___, forming the ___

Labia majora, round ligament of the uterus

The ___ are mesodermal invaginations of the lateral surfaces of the urogenital ridge that persist in females

Paramesonephric ducts

The ___ are mesodermal invaginations of the lateral surfaces of the urogenital ridge that degenerate in females

Mesonephric ducts

The cranial portions of the paramesonephric ducts form the ___

Uterine tubes

The caudal portions of the paramesonephric ducts fuse at the midline to form the ___

Uterovaginal primordium

When the uterovaginal primordium forms, it brings together two peritoneal folds to form the ___

Broad ligament

The uterovaginal primordium eventually develops into the ___, ___, and ___

Uterus, cervix, superior 1/3 vagina

The paramesonephric ducts project into the dorsal wall of the ___ and induce the formation of the ___ from the ___

Cloaca, sinovaginal bulbs, urogenital sinus

The sinovaginal bulbs fuse to form the ___, which undergoes ___ to form the ___

Vaginal plate, canalization, inferior 2/3 vagina

The sinovaginal bulbs/vaginal plate form from which embryological layer?

Endoderm

Formation of cysts in the female genitalia is most commonly related to ___

Vestigial remnants

Mesoderm proliferates around the cloacal membrane to cause ectoderm to rise and form which three general structures?

Phallus, urogenital folds, labioscrotal swellings

What does the phallus eventually develop into in females?

Clitoris, crura, bulbs of vestibule

What do the urogenital folds develop into in females?

Labia minora

What do the labioscrotal swellings develop into in females?

Labia majora, mons pubis

The ___ includes stages of physical development

Tanner scale

During the development of the male gonads, ___ develop from the gonadal ridge and incorporate ___ with a ___ genotype

Primary sex cords, primordial germ cells, XY

In males, the secondary sex cords form what three structures?

Seminiferous cords, straight tubules, rete testis

The seminiferous cords consist of what two cell types?

Primordial germ cells, Sertoli cells

The mesoderm between seminiferous cords contains what type of cells?

Leydig

When do the seminiferous cords canalize?

Puberty

In males, the ___ extends from the caudal pole of the testes to the scrotum and assists with the descent of the testes

Gubernaculum

The remnant of the gubernaculum anchors the testes within the scrotum and is called the ___

Scrotal ligament

The peritoneum evaginates along the gubernaculum to form the ___

Processus vaginalis

The processus vaginalis is mostly obliterated except for the distal portion, which becomes the ___ of the testes

Tunica vaginalis

Under the influence of ___, the ___ and ___ regress in males

Mullerian inhibiting factor, paramesonephric ducts, uterovaginal primordium

The ___ develops as part of the urinary system, and in males, becomes which three structures?

Epididymis, seminal vesicles, ejaculatory duct

A few of the mesonephric tubules (urinary system embryology) form the ___

Testicular efferent ductules

What does the phallus form in males?

Glans, crura, bulb

What do the urogenital folds form in males?

Penile raphe

What do the labioscrotal swellings form in males?

Scrotum

Does the processus vaginalis have any adult structures in females?

No